¹⁸F-Fluorodeoxyglucose is glucose in which the hydroxyl group in the position 2 has been replaced by a radioactive fluorine atom. ¹⁸F is a positron emitter with a half-life of 110 min. ¹⁸F-deoxyglucose is used in nuclear medical diagnostics and primarily used for tumor and brain diagnostics.

The compound is transported into the cell through the cell membrane and phosphorylated, but unlike glucose, it is not further metabolized. It accumulates in the cell. Since glucose transporters are stongly overexpressed in tumors, tumors accumulate an unproportionally large amount of fluorodeoxyglucose. This is the reason for the otherwise unreachable tumor contrast, which can be achieved with this compound.